📄 （9）profiles and levels in mpeg-4.htm
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<P align=center><FONT size=4><B>Profiles and Levels in MPEG-4: Approach and
Overview</B></FONT></P>
<P align=center><FONT face="Times,Times New Roman"><B><I>Rob
Koenen</I></B></FONT></P>
<P align=center><FONT face="Times,Times New Roman" size=3>KPN Research<BR>St.
Paulusstraat, 4, 2264 XZ Leidschendam, The Netherlands<BR>E-mail:
r.h.koenen@research.kpn.com</FONT></P>
<P><FONT face=Arial size=4><B>Abstract</B></FONT></P>
<P><FONT size=2>Profiles and Levels in MPEG-4 are standardised in order to give
users a number of well-defined and well-chosen conformance points. They serve
two main purposes: 1) ensuring interoperability between MPEG-4 implementations,
and 2) allowing conformance to the standard to be tested. Profiles exist not
only for the Audio and Visual parts of the standard (<I>audio profiles</I> and
<I>visual profiles</I>), but also for the Systems part of the standard, in the
form of <I>graphics profiles</I>, <I>scene graph profiles</I>, and an <I>object
descriptor profile</I>. Different profiles are created for different application
environments. The policy for defining profiles is that they should enable as
many applications as possible while keeping the number of different profiles
low. MPEG has defined a first set of profiles for MPEG-4, but more are expected.
MPEG will be restrictive in defining any new profiles, listening carefully to
what its users have to say.</FONT></P>
<P><FONT size=2>keywords: MPEG-4, profile, level, conformance, MPEG-4 video,
MPEG-4 audio, MPEG-4 Systems, interoperability, interworking </FONT></P>
<P><FONT face=Arial size=4><B>1 Introduction</B></FONT></P>
<P><FONT size=2>An often encountered criticism of the MPEG-4 Standard concerns
its size and complexity. The complaint is that the standard is too big and
unwieldy to implement. This is true梐t least it would have been without the
existence of profiles and levels. (See [1,2] and the other articles in this
issue for an overview of the object-based multimedia content representation
standard MPEG-4.) This article will describe MPEG-4抯 Profiles and Levels and
the philosophy behind their definition.</FONT></P>
<P><FONT size=2>Profiles are known from MPEG-2 Video [3] where the most used
profiles are 慚ain⌨️ 快捷键说明
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